The National Elevation Dataset (NED) consists of high precision

topography Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sci ...

or ground surface elevation data (

digital elevation model A digital elevation model (DEM) or digital surface model (DSM) is a 3D computer graphics representation of elevation data to represent terrain or overlaying objects, commonly of a planet, Natural satellite, moon, or asteroid. A "global DEM" refer ...

) for the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. It was maintained by the

USGS The United States Geological Survey (USGS), founded as the Geological Survey, is an government agency, agency of the United States Department of the Interior, U.S. Department of the Interior whose work spans the disciplines of biology, geograp ...

and all the data is in the

public domain The public domain (PD) consists of all the creative work to which no Exclusive exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly Waiver, waived, or may be inapplicable. Because no one holds ...

. Since the 3D Elevation Program came online, the NED was subsumedThe National Map elevation informati

/ref> into

The National Map ''The National Map'' is a Collaboration, collaborative effort of the United States Geological Survey (USGS) and other federal, state, and local agencies to improve and deliver topographic information for the United States. The purpose of the eff ...

as one of its layers of information.

Sources

The NED dataset is a compilation of data from a variety of existing high-precision datasets such as

LiDAR Lidar (, also LIDAR, an acronym of "light detection and ranging" or "laser imaging, detection, and ranging") is a method for determining ranging, ranges by targeting an object or a surface with a laser and measuring the time for the reflected li ...

data (see also National LIDAR Dataset - USA), contour maps,

USGS DEM The USGS DEM standard is a geospatial file format developed by the United States Geological Survey for storing a Raster graphics, raster-based digital elevation model. It is an open standard, and is used throughout the world. It has been superseded ...

collection,

SRTM The Shuttle Radar Topography Mission (SRTM) is an international research effort that obtained digital elevation models on a near-global scale from 56th parallel south, 56°S to 60th parallel north, 60°N, to generate the most complete high-resol ...

and other sources which were reorganized and combined into a seamless dataset, designed to cover all the United States territory in its continuity.

Formats

Data is available in a few popular formats such as

ESRI Environmental Systems Research Institute, Inc., doing business as Esri (), is an American Multinational corporation, multinational geographic information system (GIS) software company headquartered in Redlands, California. It is best known for ...

ArcGRID,

GeoTIFF GeoTIFF is a public domain metadata standard which allows georeferencing information to be embedded within a TIFF file. The potential additional information includes map projection, coordinate systems, ellipsoids, datums, and everything else nec ...

, BIL, GridFloat, and a few others. A version of the NED calle
EDNA
(Elevation Derivatives for National Applications) has been processed or "conditioned" for hydrologic applications. This is useful for hydrologic modeling, watershed delineation, or finding downstream flowpaths, "facilitating flood analysis investigations, pollution studies, estimations of annual streamflow, and hydroelectric power generation."

Precision

Depending on area location, the datasets are provided with 1/9 (about 3 meters), 1/3 (about 10 m) and 1-

arcsecond A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

(about 30 m) precision.

References

External links

Elevation data in The National Map

Shaded Relief Maps of the United States
Cartography Digital elevation models {{geomorph-stub